1. Field of the Invention
The present invention relates to a novel polyarylene sulfide composition and a molded article prepared from the same. More particularly, the present invention relates to the novel polyarylene sulfide composition which is excellent in platability, including good adhesion and gloss of the plated material as well as short etching time, and which can provide molded articles with high mechanical strength, and to the molded article prepared from the polyarylene sulfide composition.
2. Description of Related Art
Recently, polyarylene sulfides have drawn greater attention as engineering plastics having excellent heat stability, chemical resistance, electric insolubility and so on, than engineering plastics such as polycarbonates, polyamides, polyacetals, polyethylene terephthalates, modified polyphenylene ethers, polysulfones, and polyether sulfones.
Such polyarylene sulfides, however, are so poor in ductility and are so brittle that they are not good for use as industrially functional parts, if they are used singly. Thus, they have recently been used in combination with fiber reinforcement such as glass fibers, thereby yielding fiber-reinforced polyarylene sulfides with significantly improved mechanical strength, toughness, heat distortion resistance and so on, which in turn lend themselves to various electronic equipment parts, electrical equipment parts for vehicles, and so on.
The fiber-reinforced polyarylene sulfides are thermoplastic resins as well as have the foregoing characteristics so that, unlike thermosetting resins such as epoxy resins, they are injection-moldable and mass-producible, they do not require fabrication, such as forming through-holes and so on, and they are integrally moldable to form integral articles such as board-casing or board-connecter intergral parts. Due to those advantages, they recently expanded their use to electronic parts, such as printed circuit boards, and housings for preventing EMI (Electro Magnetic Interference).
When the polyarylene sulfides are intended to be used for the above-mentioned use, there is required remarkable platability, such as excellent plate adhesion and plate gloss and a short etching time as well. As the polyarylenesulfides do not have a phase-separate structure, unlike ABS or the like, it is required that plate adhesion be improved by means of the anchoring effect by etching of a filler. The polyarylene sulfides themselves, however, have excellent chemical resistance so that the composition of an etching solution may be subject to restriction to a considerable extent.
In order to improve platability of the polyarylene sulfide resin compositions, various attempts have so far been made. For instance, (1) Japanese Patent Unexamined Publication (kokai) No. 54,290/1984 discloses a metal-plated article consisting of glass fiber-reinforced polyarylene sulfide and having adhesion (peel strength) of ca. 1.5 kg/cm. (2) Japanese Patent Unexamined Publication (kokai) No. 23,462/1985 discloses a method for improving plate gloss by etching a polyarylene sulfide only with a good solvent for the polyarylene sulfide using a filler in controlled shapes. (3) Japanese Patent Unexamined Publication (kokai) No. 270,659/1987 discloses a method for improving peel strength and gloss of appearance and shortening etching time by formulating a glass-fiber reinforced composition with potassium titanate whiskers.
The method as disclosed in item (1) above, however, requires a longer etching time and cannot improve gloss on a plate surface when only glass fibers are used. The method as disclosed in item (2) above requires a unique good solvent for the polyarylene sulfide, such as .alpha.-chloronaphthalene or the like. Such a solvent, however, is highly poisonous and treatment should be at extremely high temperatures so that a great amount of volatiles are generated, thereby polluting working circumstances and incurring the risk of fire and a burn. Thus this method cannot be said to be practical. The method as disclosed in item (3) above presents drawbacks in that it uses expensive potassium titanate whiskers, it cannot control its composition, and it incurs the risk of reducing mechanical strength.
Further, Japanese Patent Unexamined Publication (kokai) No. 354/1988 proposes a resin composition containing 20-80% by weight of polyarylene sulfide and 10-75% by weight of short fibers consisting mainly of silicic acid, having a diameter of 13 .mu.m or shorter and and average length of 150 .mu.m or shorter. The resin composition cannot be said to be sufficient in mechanical strength and platability. Japanese Patent Unexamined Publication (kokai) No. 142,786/1987 proposes a method for treating an article molded from a polyphenylene sulfide resin composition containing glass fibers or a mixture of glass fibers with an inorganic filler with a hydrofluorate solution containing hydrofluoric acid. The method does not provide the molded article having a sufficient degree of mechanical strength and platability.